Sleep Diagnostics

Initial Assessment Tools - Sleep Sleuthing Starts

Crucial for guiding sleep disorder diagnosis.

• Clinical History: Note snoring, excessive daytime sleepiness (EDS), witnessed apneas.
• Validated Questionnaires:
  • Epworth Sleepiness Scale (ESS): Measures daytime sleepiness. Score >10 = significant EDS.

    ⭐ Epworth Sleepiness Scale score >10 is a common threshold for referral for further sleep evaluation.

  • STOP-BANG Questionnaire: OSA risk screen. Score ≥3 = high risk.
    • 📌 Snoring, Tired, Observed apnea, Pressure (BP), BMI >35, Age >50yrs, Neck >40cm, Gender (Male).
• Sleep Diary: 1-2 week log of sleep-wake patterns; tracks habits, sleep duration.

Polysomnography (PSG) - Gold Standard Snooze Study

Polysomnography (PSG) is the comprehensive, attended, overnight sleep study.

• PSG Components:

  • EEG (Electroencephalogram - brain activity)
  • EOG (Electrooculogram - eye movements)
  • EMG (Electromyogram - chin/limb muscle tone)
  • ECG (Electrocardiogram - heart rate/rhythm)
  • Airflow (nasal/oral thermistor/cannula)
  • Respiratory effort (thoracic/abdominal belts)
  • SaO2 (Pulse oximetry - oxygen saturation)
  • Body position sensor
  • Snoring sensor (microphone)
  • Video recording (optional, for parasomnias)

• Key Parameters Derived:

  • Sleep Stages: N1, N2, N3 (Slow-Wave Sleep), REM
  • Apnea-Hypopnea Index (AHI): $AHI = \frac{(\text{Apneas} + \text{Hypopneas})}{\text{Total Sleep Time in hours}}$
  • Respiratory Disturbance Index (RDI)
  • Arousal Index
  • Periodic Limb Movement Index (PLMI)
  • Oxygen Desaturation Index (ODI)

• AHI Severity Classification (AASM):

  Severity	AHI (events/hr)
  Normal	<5
  Mild	5-15
  Moderate	15-30
  Severe	>30

⭐ The American Academy of Sleep Medicine (AASM) scoring criteria are the standard for interpreting PSG data.

MSLT & MWT - Daytime Doze Detectives

MSLT (Multiple Sleep Latency Test):

• Purpose: Objective sleepiness measure; Dx narcolepsy, idiopathic hypersomnia.
• Protocol: 4-5 naps (20min), 2hr intervals, post-nocturnal PSG.
• Key Findings:
  • MSL <8 min = pathological sleepiness.
  • ≥2 SOREMPs (Sleep Onset REM Periods) for narcolepsy Dx.

MWT (Maintenance of Wakefulness Test):

• Purpose: Assesses ability to stay awake.
• Protocol: 4 trials (40min each), dark, quiet room.

HSAT & Actigraphy - Portable Sleep Spies

HSAT (Home Sleep Apnea Test):

• Types & Parameters:
  • Type III: Measures ≥4 channels (e.g., airflow, effort, SaO2, heart rate).
  • Type IV: Measures 1-2 channels (e.g., SaO2, airflow).
• Indications: High pre-test probability of moderate-to-severe uncomplicated OSA.
• Limitations: Not for significant cardiorespiratory comorbidities or other sleep disorders (e.g., PLMD, narcolepsy).

Actigraphy:

• Principle: Wristwatch-like device; records activity/rest patterns.
• Uses:
  • Insomnia assessment.
  • Circadian Rhythm Sleep-Wake Disorders (CRSWD).
  • Monitoring sleep patterns (weeks).

⭐ Actigraphy is particularly useful for diagnosing Circadian Rhythm Sleep-Wake Disorders like Delayed Sleep-Wake Phase Disorder.

High‑Yield Points - ⚡ Biggest Takeaways

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